"one who advocates socialism," 1827, from French socialiste, or else a native formation based on it, in reference to the teachings of Comte de Saint-Simon, founder of French socialism. The word begins to be used in French in the modern sense c.1835. Socialista, with a different sense, was applied 18c. to followers and pupils of Dutch jurist Grotius (1583-1645), from his use of socialistus. Socialist realism attested from 1934.

I find that socialism is often misunderstood by its least intelligent supporters and opponents to mean simply unrestrained indulgence of our natural propensity to heave bricks at respectable persons. [George Bernard Shaw, "An Unsocial Socialist," 1900]

Prison is a Socialist's Paradise, where equality prevails, everything is supplied and competition is eliminated. [Elbert Hubbard, "The Note Book," 1927]